Our Client is a secondary lead smelting plant, based in Europe, that produces mainly lead ingots for automotive car batteries, lead alloys and lead shot for hunting and sport shooting.
The Client has a recovery plant for lead acid batteries, capable of separating the different components of batteries by wet system, with neutralization of electrolyte sulphuric acid. While the segregated lead can be used as feed for the melting furnaces and re-used to build new batteries, the sulphuric acid needs a specific treatment plant to be recycled as sodium sulphate. The plant is run in accordance with ISO-90021 System Assessment of Quality. The total production of wastewater generated by batteries recovery operations on site was over 15.000 tons per year, waste that the company had to disposed of, off site.
The Solution provided
In order to reduce the ever increasing disposal costs, the company implemented a project based around the principle of reducing waste volumes by vacuum evaporation. The disposal costs saved by this project provided a ROI of less than two years. The EVALED™ TC 60000 provided a thermal separation of the wastewater into two streams, a distillate and a concentrate. The distillate representing nearly 60% of the inlet volume, was in compliance with the regulation in force and was recycled back to the process as rinsing water. The concentrate which was around 40% of the initial volume, was a solution over the solubility level, having a big quantity of sodium sulphate that was separated as wet salt. The implementation of the water treatment based on evaporation gave the site the ability to obtain the ZLD, which is becoming more and more significant given the trend of environmental legislation. The reduction in wastewater disposal volumes was the key factor in the economic return.
Results & Benefits
The distillation yield of the installed equipment has shown a consistent performance: 60% distillate having low hardness and low conductivity; 40% concentrate from which it was possible to recover the salt. This allowed the Client to reuse the distillate as rinsing water, thus reducing the site demand for fresh mains water and leading to further savings. The company has reduced dramatically the costs of waste disposal and has been able to demonstrate to the local authorities and the local community that they have a pro-active and responsible attitude to their environmental obligations.
- Matter recovery: salt from the concentrate
- ZLD: the distillate used as rinsing water
- ROI of less than two years